Convention for users to opt out of A/B tests?

An associate was unable to follow a set of basic instructions I made for using a common website. It turned out my user was on some A/B test and was served a different UI. When I checked the same site from another account, I see the standard version of the site, and I can see why my colleague was unable to follow my instructions - part of the page I see doesn't exist for them!

Question

When using a site/app to create instructions/guides for others, I want to ensure I am seeing the 'standard' version of that site.

Are there any formal, established, or 'best practice' approaches for ensuring a user receives the standard version of a site (no A/B tests)?

What I know so far

My best solutions so far are:

  • create multiple users, and compare them visually
  • write to the website and ask to be opted out of any A/B tests - they may be able to assist